Fertilizer and process for making the same



Patented Apr. 21, 1942 -UNITED STATES PATENT OFFICE- v 2,280,451 v kGriflith n. Biddle, Brookline, Mass, assignor to Research Foundation,Inc., Wilmington,-Del., a corporation of Delaware No Drawing.

Application November 25, 1939, Serial No. 306,195

14 Claims. (Cl. 71-2 This application isa consolidation andcontinuation-in-part of my co-pending applications filed June 11, 1987,and serially numbered 147,712, 147,713, 147,714, 147,718, 147,719,147,720.

The purpose of this invention is to provide a fertilizer materialcontaining at least three of the 64 minor elements, as defined inagronomy, in a form that may produce plant stimulation without danger oftoxic eifects such'as are evidenced TABLE I groupings, one of eightelements, entitled usually contributed in complete mixed fertilizer andthe other, two elements, entitled invariably found in all soil. Theseeight elements in one group are now generally known as the majorelements, to differentiate them from those included in the minor elementgroup. Frequently this group of major elements is considered to containa silicon and aluminum found in the other group because the quantityoccurrence of all of them in plant life is such that they seem entitledto this classification. These 10 elements will be referred to hereafteras major elements.

This eliminates 28 from consideratiomleaving 64 which will be referredto hereafter as minor elements. The hst follows:

TABLE II Iron Tin Indium Yttrium Titanium Tungsten caesium YtterbiumManganese Beryllium Germanium Dysprosium Chromium Molybdenum ZirconiumTerbium Barium Cadmium Hainium Erbium Strontium Bismuth Tantalum HolmiumZinc Lithium Columbium Thulium Lead Mercury Rheuium Lutecinm BoronSelenium Masurium Europium Arsenic Tellurium Cerium Gadolinium CopperBromine Lanthauum Thorium Fluorine Vanadium Praseodymium Uranium lodmeSilver Neodymium Actinlum Nickel Rubidium lJlinium Polonium AntimonyGallium Samarium Protoactinium Cobalt Thallium Scandium Radium I haveused all of the above minor elements in combinations.

at least one of theirforms in my agricultural experimental work eitherseparately or in "various In recent years the extreme importance of theminor elements and-their relation to plant stimulation, growth, anddeficiency 'diseases has come to be increasingly appreciated by both theagronomist and plant physiologist. M0st of-the experimental agriculturalstations in this country and in the major countries abroad have beenexperimenting with a view to determining the functions of minor elementsin plant life. Such work has been seriously handicapped because of theimminence of toxicity due to'the use of watersoluble salts as a sourceof the minor elements.

The quantity of any such water-soluble salt which may be used to bestadvantage on any particular soil for any particular crop must be 40 Thepreceding table contains two element determined experimentally in thefield by trial and error methods. The amount of. any such salt foundmosteffective .for optimum stimulation without toxicity on one soil type mayprove toxic on another because the critical amount of such applicationvaries widely between soil types as well as among diflerent kinds ofplant life.

Conclusive tests are, therefore. diflicult to obtain for a few crops oneven a single soil type, and the constant drain on the minor elementscontained in the soil, due to harves ng, causes such results to beinadequate for reference in future use.

Common practice inthe application of watersoluble salts in the fieldconsists of a single apcreating an environment unnatural to the plantwhich, of necessity, must assimilate an abnormal quantity of such ionsif the application is substantially in excess of current plantrequirements.

When this occurs toxicity usuall results, although in some soil typeslack of moisture or the presence of bufier factors may afford someprotection.

I have discovered that the minor elements may a .be used to provideoptimum stimulation without fear of toxicity, providing properlymanufactured substantially water-insoluble inorganic forms are used astheir source, which difi'erentiate them from water-soluble salts as toimmediate availability for assimilation the limiting factor againsttoxicity is then the kind and quantity of acids present in, the soil towhich they are applied. t

It has been established that those soil types which are commonlyconsidered fertile have a pH between the limits of pH 4.5 and pH 6.75.Other soil types having a pH more alkaline and some more acid are knownand are used for agricultural purposes, but these are not usuallyprolific nor generally considered good agricultural soils. Severalthousand different soil types have been identified by the Soil SurveyDivision of the Bureau of Chemistry and Soils of the United StatesDepartment of Agriculture. These have not been classified according topH but as might be expected their pH range varies within all possible pHlimits of soil.

I have found that to obtain optimum results with my new fertilizermaterial it should be man'- ufactured so that its surface area exposedto the soil acid solutions, and so vulnerablefor soluplication, suchapplication being in an amount sufliclency of all but one of'them. Mostgood agricultural soils would show a deficiency of a substantial numberof such elements it a complete analysis were made, while many ordinaryagricultural soils could be shown to be deficient in a large number ofthese elements. All such soils, however, enjoy a definite suiliciency,to excess of asubstantial number of certain of these elements, suchexcess sometimes being suflicient for agricultural purposes for hundredsof years.-

("Element Assimilation by Plant Life With Reference AbstractBibliography, Riddle, 1938, p. 94.)

Because all soils have element deficiencies, only by quantitativeanalyses of .the same species of plant grown on many soils, then takinga mean or .average cross section of determinations for each element soanalyzed can the saturation con- .stant specific to the plant for thatelement be ascertained. This is the procedure which I followed in myexperimental work to determine the saturation constant specific to anumber of plants for many elements. This work was carried out on 28crops obtained from 32 states.

Specimens used in this analytical work were usually purchased in carloadlots, and the work extended over a period of approximately three years.

bility, is correlated to the acidity of the soil type upon which it isto be used, and since I use at least three of the 64 minor elements, Ihave found it best that the specific surfaces of all forms so used beproportional to their relative rates of solubility, and that weightdistribution of particle size should diminish uniformly.

Ihave discovered that reciprocal element assimilation, of the ions ofall the elements present in excess, 'assimilable by the plant, iseffected by plant life in the event of a deficiency of any of them inthe soil. The quantity of each of all such elements so assimilated, inthe event of a deficiency in any single element, is proportional to thesaturation constant specific to the plant for each of them. The amountof any element which is normally assimilable by any given plant iscontrolled by the quantity and kind of organic acids synthesized by thatplant. Ref: Element Assimilation by Plant Life," Riddle, 1938.

The term "saturation constant specific to the plant is used herein todesignate the quantity of any element which a species of plant wouldassimilate if there were no solid deficiencies. This varies widelybetween different types of plants.

The quantity of each of the elements assimilated by all types of plantlife is consistently the same for any particular species of plant.providing there are no soil deficiencies. No soil contains a suiliciencyof all of the elements common to plant fluids nor does any soil containa (ill The following three tables, III, IV and V illustrate thesaturation constant specific to the plant for barium, manganese, andiron in several plants. Table III shows the variation of barium contentin several different kinds of plant leaves (dry basis); Table IV showsthe variation of manganese content in several different kinds of plantseeds (dry basis) and Table V shows the variation of iron content inseveral difi'erent kinds'of entire plants (green basis). The datacontained in these tables, particularly Table V, furnish conclusiveevidenceof varying saturation constants specific to the plant.

Wild-olive leaf Showing different analytical results obtained from(llL']l--\A'ltll greatest variation more than 15 to l.

TABLE IV MANGANESE (Dry basis) Plant seeds Per cent Hemp 0. 0105 Tobacco007- l Oats, six variet 0050 Wheat, ton varieties. .0017 (-rimsonclover. .(KIZJ Sunflower"... .0023 Beans, five var .001 Alfalfa .0012

Showing giiil'erent analytical results (ihlalinml from each withgreatest variation more than 13 i l.

TABLE V Iron (Green basis) Entire plant Per cent Parsley. 0.0l9'3lpinach .00250 lettucagm'nloai .00187 Watercress .00124 (abbage,n-d. 1.00104 (abbage,grcen .00079 Shows different analytical results obtainedfrom cachwi1h 1 greatest variation more than 24 to l.

Barium-Ref.-Minor Elements" Ref. Abst. Bib.

Riddle, #501, 1938;

,ManganeseRef.Jour. Agr. Res. 23, 395, 1923'.

IronRef.U. S. Dept. of Agr. Cir. 205, Feb.,

containing them which have been processed toany of my specifications areground finely enough so that such mineral values are completely unlockedfrom the accompanying gangue.

This is of considerable value because it preeludes the necessity oftesting future lots of ores" purchased which likewise containthoseminerals previously tested. This would hold true even if the formcontaining the minor element was either metallic or elemental. If it isnot feasible to ascertain the relative rate of solubility of the mineralas compared to others that may be used, but one prefers to test theentire ore containing such minerals, a correction factor may be usedbased upon the relative rate of solubility of the gangue, taking intoconsideration its quantity occurrence in the me as this is usuallymeasurable. Such gangue content consisting of undesirable minerals maybe substantially disregarded in arriving at a solubility factor.

The rawmaterials comprising the minor elements which I use incompounding my fertilizer material are usually ores or minerals,although elements, industrial by-products or' wastes, electrolyticslimes, or inorganic synthetic compounds may be used. 'I prefer to useores. Regardless of the form selected it should be analyzed for'itscontained minor element content so that predetermined amounts of suchelement may be applied. The raw material should then be manufactured sothat it has the requisite specific surat a definite and uniform ratethus preventmg a deficiency of any one of them, at any time,

' prior to the complete solution of all, and this, ir-

respective of the quantity of any minor element used.

The intensiveproperty, specific surface. has

proven to be invaluable in the preparation of ac-' curate grindingspecifications for the-forms of the minor elements to be used in my newfertilizer material. It has made possible the introduction of density insuch calculations so that a proper coordination could be given tosurface followed by further dissociation of the organic acids present,to maintain their dissociation constants, thereby aiiording new hydrogenions available for continued solubility, this must in-- variations aswell as the type of soil aggregate.

These factors actuatathe transient soil solution movements and therebycontrol the rate of difiusion of all ions in such solutions.

Unfavourable conditions may exist over short periodsof t'me during whichdiffusion would be, inhibited and solubility of the forms of the minorelements in soil during these periods retarded.

. This is a condition common to all soils, and in correlating relativerate of solubility of a subface. This is ascertained from its solubilityfacf tor and such requisite specific surface may then be embodied in auniformly diminishing distribution of particle size in any formprocessed. A correction factor may be introduced to compensate for thepH of the soil after specific surface has been determined in thismanner. Optimum results will be obtained if the above procedure isfollowed. 1

This is most important because, by this method, each form of a minorelement used may be manufactured so that, when compounded with forms ofother minor elements, the rate of solubility of each will be such thatall of them will dissolve stantially water-insoluble compound to a givenpH it must be taken into consideration, because such calculations arebased upon time and inhibited difiusion for periods of time would be thesame .as increasing the pHproportionally.

It is not generally appreciated that the quantity of acid in, any soilwhich is dissociated and therefore available to'efiect solubility of anyforms of I the minor elements is comparatively small. Neither is itappreciated that such quantity in any given soil is comparativelyconstant per unit of time. However, this is the case, and the extent ofreactivity between acid and forms of the minor elements is limited tothe quantity of such dissociated acid present and the rate of difiusionwhich aifords a replacement of any of the hydrogen ions that may havebeen consumed in the reaction which effects solubility of any forms ofthe minor elements.

When my new fertilizer material containing at least three forms of theminor elements is applied to the soil, there is available to eachunitweight so applied a specific quantity of acid, to

effect solubility be"ause under normal conditions the greater the amountof such material applied, the more'H-ions there are available to it, dueto the surface and volume which it occupies in the soil, the soil pHbeing comparatively constant, dsregarding rate of diflfusion of soilsolutions. That constituent of the comminuted material which entertainsthe largest surface "will enjoy the greatest portion of the givenquantity of acid available to the entire unit weight. Due to theelements thus aflorded to the plant from all forms used per unit of timeis proportional as predetermined, the importance of correlating specificsurface of two, three or more forms, simultaneously applied, lies in thefact that this correlation determines the relative number and weight ofthe ions of each of the minor elements that are made availablesimultaneously in that given time.

Since I use at least three forms of the minor,

elements, not only should their specific surfaces be correlated, butalso if more improved results are to be achieved, each should have auniformly increasing distribution of surface. Predetermined relativesolubility of all forms of the minor elements used can only bemaintained without erratic fluctuations providing the skew frequency vor weight distribution of particle size is uniformly diminishing foreach. Thiscan only be achieved by utilizing a closed circuit whengrinding for a specific surface falling within the critical range ofclin /gm. and emf/gm.

For example, consider a case in which we have two forms of the minorelements so ground that neither has a uniformly diminishing distributionof surface although both are vulnerable to the soil solutions whenapplied. I have stressed the importance of a definite ratio between thequan-. tity of the ions of the various minor elements available to theplant at all times to avoid sporadic deficiencies.

As solubility of these hypothetically ground forms begins, there existsa ratio of ions available to the plant proportional to'the ratio of theimmediately exposed surfaces to the soil acids. As the surface of eachform disappears with progressive solubility, the ratios of exposedsurface of each of them would change with respect to each other. Hence,the ratio of ions contributed to the solution would vary in the samedegree that the exposed surfaces of each of the forms varied withrespect to each other. The more the specific surfaces depart fromuniformly increasing states, or the total surfaces depart from uniformlydecreasing states, the greater will be the variations in the ratios ofavailable ions, thus causing reciprocal element assimilation to agreater or lesser degree. Such reciprocal element assimilation isresponsible for toxicity in plant life.

Preferential selectivity exhibited by plants in the assimilation ofconstant quantities of the ions of any of the elements which theyrequire is today well nown. Such preferential ability may be exercisedby the plant without deviation from the saturation constant specific tothe plant for each element only in the event that a sufliciency of ionsof all such elements are available to the plant root membrane. Thissituation presumably never occurs because of at least some deficienciesoccurring in every soil.

The degree of abnormality which may be caused within a plant due toan'over-assimilation of any the plant for all 74 assimilable elements,providelement is determined by the degree to which the ions in the soilsolutions are unbalanced with respect to that point. If this isexcessive at any given time, due to an erratic presentation of ions forassimilation, toxicity will occur and the degree of such toxicity due toover-assimilation will be proportional, as the excess of assimilatedions of any element is to its saturation constant speciflc to the plant.

A good example is an over application of a water-soluble salt containingany one of the 64 minor elements. Toxicity invariably occurs due to theerratic change in the presentation of ions when such salt is so applied.If but a small quantity is used in excess, toxicity would only beevidenced by growthinhibition which might even pass unnoticed unlesscompared with a control plat.- 0n the other hand, if the amount isincreased unduly, such application can prove lethal.

It is believed that even a slight excess in any plant, of any element,essential or stimulating to it, would cause some toxicity to that plantirrespective, of the saturation constants specific to ing any one ofthem,were deficient, thus permitting even negligible amounts of othersto be assimilated in excess. However, early stages of such toxicity areneither measurable nor visually apparent.

Toxicity to a plant due to an over-assimilation of the elements isproportional to the degree of such over-assimilation, and the point atwhich such toxicity becomes either measurable or visually apparentdepends upon the type of plant and soil media. Wide variations betweensaturation constants specific to plants cause certain of them,

whose saturation constants for'certain elements are low, to beparticularly sensitive to an overassimilation of such elements, whileothers, whose saturation constants for specific elements are high,exhibit greater degrees of tolerance. Therefore, an application whichmight prove toxic to one plant may be beneficial to another.

' The particle size range, derived from grinding any substantiallywater-insoluble inorganic forms of the minor elements, which lies withinthe limits from minus 200 mesh down to one micron exhibits certainphysical characteristics which are not encountered in any other grindingrange. This is substantiated by semi-logarithmic graphs drawn from dataof commercial ore grinds compiled by Arthur J. Weinig of the ColoradoSchool of Mines, covering some 25,000,000 tons of various ores from manylocalities. Such data are available in the following publications:

July quarterly of Colorado School of Mines,

1933, entitled "A Functional Size-Analysis'of Ore Grinds, by Arthur J.Weinig.

October quarterly of Colorado School of Mines.

1937, entitled The Trend of Flotation," by Weinig and Carpenter.

Such curves showthat in the range below 200 mesh down to one micronthere is a uniformly diminishing weight per cent of particle sizethroughout the entire range. This uniformly diminishing weight per centof particle size is'in fact predictable mathematically when the weightdistribution lying on any two ordinals within this range is known.

The slope and position of a curve in this critical range as depicted ona semi-logarithmic graph can be changed by varying the conditions ofgrinding, thus affording control of' particle size distribution withoutaltering uniform diminution of weight or uniform increase of surfacedistribution.

A. J. Weinigs sole interest in the minus 200 range was its usefulness asapplied to ore classification and the recovery of values in the miningmy methods of processing my new fertilizer material. It ischaracteristic of this range that only within these limits does weightdistribution of particle size decrease and weight distribution ofsurface increase proportionally for allforms of the minor elements used.It is likewise within this critical range only, that erratic variationsin the ratios of available ions may be avoided, as between any two ormore of such forms, simultaneously applied, thereby permiting a definitecorrelation between the solubilities of each and concurrently inhibitingreciprocal element assimilation by the plant for these elements.

The lower limit of the critical range terminates at one micron and thisis of considerable importance. Particles whose diameter size is lessthan one micron are today conventionally considered to fall within theso-called colloidal range.

Material of this character which is intended to be used as a fertilizerenjoys substantially the same rate of solution, in the soil solutions,as do watersoluble salts, due to its enormous surface area.

Field and water culture experiments conducted by some 400 of the worldsleading agronomists have proven the imminence of toxicity whenwater-soluble forms of the minor elements are used. Experimental work ofthis character has been conducted by them in carefully controlled testsusing more than 60 per cent of the 64 minor elements individually.Abstract references on this work from the technical literature have beencompiled and may be found in The MinorElements, Their Occurrence andFunction in Plant Life, Ref. Abst. Bib., .Riddle, 1938. Still morerecent work has considerably amplified the list of those elements used,as may be ascertained by consulting the technical literature coveringthe last 18 months. Every form containing aminor element which has todate been tested, either in the field or in water culture experimentalwork, has proven to be toxic to plant life if used for fertilizer inthe'form of a water-soluble salt, and in an amount in excess of that towhich the particular plant is accustomed.

The susceptibility of colloidal particles tosolubility in the soil acidsolutions may be readily appreciated; their ions are thus presented tothe plant root substantially as rapidly as would be the case ifwater-soluble salts were used. Therefore, an application of colloidalparticles containing'the minor elements, to numerous soil types, formany plants whose saturation constant specific to the plant is low forthat particular element, might result in toxicity. This situation isanalogous to that which occurs when water-solu=ble forms are used.

In calculating the specifications to which I wish to'manufacture my newfertilizer material, by one of my preferred methods, the pH of the soilto which it is to be applied, as well as the and soil solution difiusionrates, must be considered.

minor elements used to a specific surfacein that proportion to whichthey had been correlated according to their relative rates ofsolubility, ancl' as coarsely as the most soluble one of them permitted,but still maintain the entire particle size distribution of all of themwithin the critical range. I have found that the coarsest mean particlesize diameterof any properly comminuted form of the minor elements whichI can best use on any soil type is approximately 60 microns, thecoarsest particle size diameter in the entire distribution being nogreater than 74 microns. The specific surface that corresponds to thisdistribution is emf/gm.

where D5 is the density ofthat form used.

If the pH of the soil is high, such as pH 6.75,

I would then grind each form of the minor elements used inthatproportion to which they had been correlated according to their relativerates of solubility, and-as finely 'as the least soluble cm. /gm.

clnF/gm.

ticles could be considered spheres. This being the case:-

Where; Ds=density of form used Specific surface:

=mean particle size diameter in microns of form .used. The foregoingexamples illustrate the lowest and the highest specific surface limitsto which I prefer to manufacture my most improved fertilizer materialfor application to soil types having limits between pH 4.5 and pH 6.75.For soil types which enjoy neither extreme of pH, my'fertilizer materialmay be prepared so that the specific surfaces of all forms of the minorelements used are correlated as to their relative rates of solubility,between these limits, with a correction factor applied for soil pH. Ifso prepared, it is the pH of the soil which finally determines therelative position as regards specific surface that each form will occupywithin the'critical range. However, I am not confined to the limitsalthough optimum results therein.

emf/gm. to emf/gm.

are usually obtained 7 Certain unusual soil types which might beconsidered to fallwithin that classification of normal or goodagricultural soils evidence peculiar.

of Agriculture; and are being investigated. For

" best results onsuch soils my new fertilizer material must necessarilybe comminuted so that correlation of specific surface between each formof the minor elements used is suchthat due consideration is given tosuch peculiar soil characteristics.

There are several major factors of which one or more may be utilized toadvantage in the methods which may be employed for obtaining thespecifications for my new fertilizer material. Each such factor makes avaluable contribution, not only to the product so processed, butcontrols the process by which such a product is obtained. Each of themrenders a valuable service in inhibiting reciprocal elementassimilation, and when all are coordinated optimum results will beachieved.

All of the products used in compounding my new fertilizer material andwhich may be prepared according to the specification are char--acterized by two basic factors, listed below:

'(1) At 'least three substantially water-insoluble inorganicforms of the64 reciprocally assimllable minor elements, each form being a source ofa designated quantity of at least one of the minor elements;

(-2) And having a specific surface within the range between low:

(a) Each said form having a uniformly diminishing distribution ofparticle size by weight (within said range);

(b) The ratio of the specific surface of each said'form to that of anyother form being'substantially inversely proportional to the ratio oftheir rates of solubility;

(c) The ratio of the specific surface of at least one form to that. ofat least one other form being substantially inversely proportional tothe ratio of their rates of solubility;

(d) The mean particle size of each form being such as to give thedesired rate of solubility in the soil upon which it is to be used;

(e) The mean particle size of each form being such as to give thedesired rate'of solubility in a soil having a pH within the range of 4.5to 6.75;

(1) Such minor element forms being occluded in at least one compoundcontaining a major element;

('g) 'Particles of the fertilizer material being bound in the form ofagglomerates by a watersoluble substance;

(It) Particles of the fertilizer material being bound in the form ofagglomerates by a watersoluble substance which includes at least onemajor element;

(i) Each form being present in the mixture in amount and having aspecific surface effective to be gradually available to produce plantstimula tion without causing objectionable toxicity;

(7') At least three of the forms being present in the mixture in amountsand having specific surfaces effective to be gradually available 'toproduce plant stimulation without causing objectionable toxicity;

(k) The availability of the minor element ions afforded by each otherform being such that they are severally nonetoxic.

The efficiency as regards stimulation, as well as inhibition ofreciprocal element assimilation will be further enhanced in any of theabove methods by the use of an increasing number of forms of the minorelements in excess of three.

I do not wish to confine myself to the use of any one of my methods, aseach of them may be used to advantage under certain conditions.

One of the methods which has been found to be satisfactory forcalculating the relative rate of solubility of any substantiallywater-insoluble inorganic compound in acid solutions, providing reliableexperimental data is available, is described hereafter, as well as thetechnique utilized in one method of determining such data andsubsequently the numerical solubility comparison factor which may beallocated to each, representing their comparative rates of solubilityunder a given set of conditions.

Relative rate of solubility technique I have found the followingtechnique to be satisfactory for this purpose. A standard conductivityapparatus was used to obtain measurements. Readings were taken in ohmsresistance indicating H-ion depletion. Such readings were obviouslyslightly bufiered by metallic or other ions contributed as solubilitywas effected and concurrently reflect depletion of the total surface.Temperature control was maintained at 25 C. within .002% of 1 F. Thethree mineral acids, HCl, HNO: and H2804 were each 'used separately in a1/50 N. solution of 250 cc. These acids were used in preference toorganic acids because at this concentration it was considered that theywere dissociated, which would not be true of any organic acid soutilized where progressive dissociation would destroy the integrity ofthe readings.

Many kinds of substantially water-insoluble inorganic compounds weretested. Most of these were ores. All samples used in such experimentalwork had been carefully prepared by grinding and only thatfraction ofthe ore grind which passed a 270 mesh Tyler Standard Screen but failedto pass a 325 mesh Tyler Standard Screen was used.' Uniformlydiminishing particle material dispersed in the solution to any appre-vciable degree.

A Wheatstone bridge was employed, the cell being the unknown resistance,standard resistance was maintained at 50 ohms. In order to determine thepoint at which the authoritative are available and this bridge isin'balance, a thousand cycle altemating current was. passed through thecircuit,-null point being ascertained by telephonic head-set. Readingswere graphically plotted, ohms resistance against time in minutes, allohms resist ance values being first corrected to a'zero point of 450ohms resistance, thus affording hyperbolic curves depicting relativerates of solubility because each curve approaches a certain-individualplane as an asymptote,

Irrespective of the fact that either pure minerals or ores had been usedin the preparation of the sample, readings 'so obtained obviouslydepicted the rate of solubility of the mineral content of the ore, as nodetectable difference- '7 due to lack of wetting, would influence thetotal curvature. Using these data a true hyperbolic curve could then becalculated from zero ohms resistance to total ohms resistance atcomplete H-ion depletion: thus furnishing data from the origin of thecurve to 450 ohms resistance, which 'were reliable throughout the entireextent of the curve and using the value obtainedon such curves at 450ohms resistance or pH 1.699, it

. was then possible to calculate the rate of solcould be observed due tothe presence of gangue,

culty was encountered in obtaining reliable readings whenthe sample wasfirst introduced into the acid solution for'two reasons: one, the timelag due to lack of wetting instantaneously and two, the human factor oferror because at this point where surface was greatest, solubility wasfastest and readings had to be made with great rapidity. This did notdestroy the integrity of the curve for our purposes as will be shownlater, and although no; solubility test was carried through to aconclusion of complete depletion of H-ions because of the enormousamount of time which would be involved, this did not constitute anobstacle as such readings were not necessary.

It should be noted that the 2 gm. sample used in all experimental workcontained an excess of metallic ions compared to available H-ions in theacid solution, as the N/50 acid solution of 250 cc, contained exactly ,5grams of H-ions which was not suflicient to effect total solubility ofall ore or mineral present and so release the total number of metallicions contained therein. Also that when ores were used the crystallinemineral content had been completely unlocked due to the fine grinding ofthe sample, so that its .entire surface was exposed to the acidsolution,

no occlusions remaining in the gangue. Each sample had beenquantitatively analyzed for its metallic content, thus assuring anexcess of metallic ions to H-ions.

Nora-The original concentration of acid in the test solution was 1/50 Nirrespective of the kind of acid and atthis concentration the ohmsresistance across the cell was invariably the same having beenmathematically corrected to 450 ohms; and because this was the point atwhich H-ion concentration was greatest as well as that point where thesurface of the sample being tested was greatest, no solubility as yethaving been effected, relative rates of solubility in grams per minuteof the mineral comprising the ore or sample were calculated to thispoint, the acidityof the solution at that time was pH 1.699. No otherpoint on the curve could have been used as there was no method knownwhereby the constantly diminishing surface could be calculated as of agiven time period. g It was ascertained from experimental data obtainedfrom testing many ores, that their rate of solubility plotted in ohmsresistance against time in minutes, invariably portrayed a hyperboliccurve. Such curves may be mathematically analyzed if values at threepoints known to be was the method which was used. ,Such points wereusually obtained in that region lying at 10 minute, minute, and minutereadings, where neither the human factor of error nor the lag,

- which consisted mainly of silicates. Great difliubility in grains/min.of the mineral content of any ore used as a sample and finally knowingthe chemical composition of the mineral it was possible to ascertain theamount of metallic ions contributed to the acid solution. Bythe simplemethod of using the factors of the logarithmic or H-ion scale it is nowpossible to determine the relative rate of solubility in grams/min. of

such a sample in an acid solution at any given was allotted to each formso tested, based upon their mean relative'rate of solubility in the mineral. acids. This may be done on anysuitable basis. These factors werethen used to ascertain, by comparison, the required proportionalspecific surface'each to the other of any two or more forms-of the minorelements which were to be used together in compounding my fertilizer material.

One method for determining numerical'solubility comparison factors Thecalculated rate of H ion depletion in %/min. of an ore or mineral in aN/ acid solution having a pH 1.699, may be determined 1. By solving thefollowing equation (XI+P+ for the value of C and substituting the valueof C so obtained in the differential equation lllf (100- Y) DX 100C andsubstituting (l for the value of Y, 0 being the N represents theultimate value of ohms re-.

sistancethat is reached at the completion of the reaction or depletionof all H-ions.

C represents a constant, indicating rate of reaction between a H-ion andthe pure mineral or ore, if used.

P represents time'lag, due to lack of wetting and human factor of error,etc. indicated by the.

point of intersection of the pure curve on the X resistance has not onlybeen measured but corrected to 450 ohms resistance.

The value of Y represents. the ohms resistance across the cell or thepercent of H-ions remaining in the solution, which in this instancewould be the original H-ion concentration of the solution, from whichsolubility data was obtained. Y likewise represents a N/50 solution witha pH 1.699.

2. The specific surface of each ore tested was obtained by solving theequation SS Daxd cmf/gm.

using known values for D5, density, and d, the mean particle sizediameter.

3. Since the gram which was considered used for experimental purposesenjoyed a different specific surface for each ore, our readings in H-vion depletion, plotted against time in minutes, could not be correlatedfor comparative purposes for the following reason. The H-ion depletionrate plotted against time in minutes for each such ore had to becorrected so that the readings indicated what such readings would havebeen had each substance enjoyed the same specific surface as the others.This was done as follows: One substance or ore was selected as a base towhich the specific surface of all others were to be corrected orcorrelated. The ore chosen for this purpose was pyrolusite which had aknown specific surface of 272 cmF/gm. By taking the specific surface ofpyrolusite 272 crnF/gm, (our base) and dividing it by the particularspecific surface of the ore or substance which is to be corrected orcorrelated to the same specific surface, the result was then multipliedby the rate of depletion of H-ions in %/min. at pH 1.699 ofthe'substance being corrected.

The %lmin. depletion rate at this point was selected because this wasthe pH of the original acid solution used for all' test purposes priorto the introduction of the sample, and therefore before any solubilitywas effected. At this point the specific surface of any such samplewould not have changed by reason of solubility.

4. The next step is to determine the H-ion depletion in g'ms./min. atN/50 solution or greatest intensity, where .005 gms. l- I-ions areavailable. This may be done by using the corrected rate of H-iondepletion in %/min. and multiplying it by the total amount of H-ions (byweight) present in the solution carrying .005 gram. The result may beexpressed as gms./min. H-ion depletion.

5. One should then determine the total weight of metallic ions whichwould be displaced when the ore containing them reacted with .005 gramof H-ions present in the solution. Taking the chemical formula ,for themineral with which such H-ions will react and determining the a valenceof the resulting compound formed after then determine the percent weightof metallic ions available as a result of the total reactloil betweenthe metal and the .005 gram of H-ions.

6. The next procedure should be to ascertain the grains per minute ofsuch metallic ions which would be contributed to the solution as aresult.

of reaction at pH 1.699 or N/50 acidity.

, This maybe done by multiplying the H-ion depletion %/min. by theweight of metallic ions displaced by .005 gram H-ions.

7. In order to' ascertain the rate of solubility of a mineral ingms./min. at pH 1.699, which contained desirable metallic ions; it ismerely necessary to utilize the chemical formula for the pure mineraland calculate the mineral weight based upon the metallic weight of thedesired element.

8. In order to obtain "numerical solubility comparison factors basedupon the relative rate of solubility of a mineral in ems/min. in an acidsolution of pH 1.699, the following procedure is employed. I

As the factors are comparison factors, they must each be related to amineral selected as a base, and for this purpose pyrolusite was chosen.Its solubility in gms./min. in an acid solution of pH 1.699 wasdetermined to be .07635. By dividing the rate of solubility in gms./min.at pH 1.699 for each mineral being used, by that of pyrolusite (base) asolubility comparison factor" indicating relative rates of solubility ingms./min. at pH 1.699 as related to the base substance, pyrolusite, maybe obtained. For convenience the decimal point in each suchdetermination was moved two places to the right in order that largernumbers mightbe obtained. This may be done without changing the relativevalue of the resultant factors. Such numbers are comparable andrepresent relative rates of solubility based upon that of pyrolusite.

Examples of mineral solubility comparison.

factors which have been determined by the foregoing method are,pyrolusite 100, galena concentrates 76.7, arsenopyrites 24.6, sphaleriteconcentrates 9.8 and millerite concentrates 6.05.

When these solubility factors have been arrived at for each ore ormineral being used, it is a simple matter to calculate the specificsurface to which each should be ground to last a definite per od of timein days indicating the growth period of the plant, and to compensate forsoil characteristics, such as soil solution diffusionrates, soil pH andperhaps others, where the material is known to be used on a specificsoil.

In the comminution to specification of each form of the minor elementscomprising my V new fertilizer material, any comminution equipment maybe employed which can be so controlled as to produce predeterminedparticle size distribution by weight within the limits of commercialgrinding. I find that a ball mill so con'-' structed that it permits acontinuous process' is most satisfactory.

Feed to the mill, or grinding apparatus, should be effected by amechanical means which affords wide variations in feed per unit of.time. This unit should be capable of adjustment to provide any desiredrate of feed.

Mill product should be introduced into a @5155- ification unit which maybe so adjusted that it is possible to effect a close separation at anypoint in the particle size distribution or skew frequency of thatcomminuted form of the minor elements, and this with a high degree ofefficiency. I find a centrifugal air classifier of proper design mostsatisfactory for this purpose.

may be controlled.

The discharge of oversize from the classifier new feed added to theoversize is the exact equivalent in weight of the fines discharged fromthe classifier. By this means a closed circuit is effected which, afterbeing operated for some time, is considered to be in balance.Thereafter, the greatest efiiciency in comminution to specification willbe attained with uniform mill discharge, and the ratio between fine andcoarse product from the classifier will then be constant.

The discharge of fines from the classifier should then be analysed toascertain the skew frequency or weight distribution'of particle size, sothat this may be compared with specifications which have been preparedfor that particular form of a minor element; any conventional method forthe determination of particle size distribution may be used for thispurpose. I prefer an approved adaptation of the hydrometer sedimentationmethod.

If the particle size analysis discloses that the finished productrepresentedby the discharge of fines from the classifier is either tooco'arse or too fine, this may be corrected by adjusting the classifier.If the quantity of fines compared to the quantity of coarse materialcoming from the classifier is believed .to be too small, this may becorrected by increasing the weight or size of the balls used in the millor decreasing the rate of delivery of the feed to the mill, or both.When a small mean particle size" diameter is desired, the ball mill isoperated with a heavy ball charge and the rate of feed is comparativelylow. When a large mean particle size diameter is desired, the ballcharge should be light and the rate of feed comparatively high. Thus byvarying the conditions of grinding and classifying the weightdistribution of particle size and surface is controlled.

In this manner it is possible to obtain a predetermined weightdistribution of particle size and concurrently a predetermined specificsurface for any form of the minor elements so processed, and no particlesize diameter need be greaterthan 74 microns nor smaller than onemicron, if desired.

To eliminate any colloidal particles that may have been produced in thegrinding operation, I use an exhaust blower and dust bag system which isoperated at the discharge end of the mill and capable of removingparticles whose particle size diameter lies below one micron.Thesecolloidal particles not only tend to aggregate and thus preventproper admixing, but may be definitely toxic when used as a fertilizerin-' gredient, their close similarity to water-soluble salts in thisrespect having been previously mentioned.

In order to obtain a low specific surface, which is frequently required,it is necessary that the mean particle size diameter be high. Thisrequires the elimination of certain finer particles in the particle sizedistribution and is accomplished. by repassing the classified materialthrough the classifier, which has been readjusted to eliminateundesirable fine material within the critical range.

It should be appreciated that no mechanical classifier as of present-dayknowledge can do more than classify within reasonably close limits,

2,280,451 The rate of feed should be adjustable so that it from a largenumber of analyses that yieldedbetter than 99 per cent within the rangedesired, using certain forms of the minor elements.

When any form of the minor elements has been processed to specificationso that it may be regarded as finished product, it should then beblended with one or more of the others to be used,

elements utilized, if the material is to be 'used' for but a specificcrop to the best advantage.

If the material is being compounded for use on a multiplicity of crops,such proportionate quantity occurrence of the minor elements in thefinal mixture should be based upon mean or average saturation-constantsspecific to the plant for many crops, this having been ascertained foreach element on all such crops.

-Such mean or average saturation constants specific to the plant formany crops would naturally be influenced within comparatively widelimits by the selection of such crops. If agroup of the leafy crops suchas spinach, lettuce, parsley, watercress, etc. were utilized in thisconnection, the mean average saturation constants group.

The same propensities of species, or types or varieties of plants,having somewhat similar characteristics, to assimilate similarquantities of certain minor elements is today well known to the plantpathologist, physiologist and agronomist. Discretion obviously must beused in any selection of a group of plants or plant species,

types or varieties from which saturation con stants specific tothe plantare to be taken and averaged, as a basis forthe calculation of specificsurface to be used in processing specifications.

Fortunately; quantitative analyses for substantially all of the minorelements in many types of plant life have been made by those wellqualified to do this work and such information today exin the technicalliterature, to which reference may be made for guidance.

My analytical work, on 28 crops which were obtained from 32 States, inwhich I made determinations on some of them for 58 of the minorelements, and on many of them for 20 or more I minor elements, hasenabled me to obtain such data.

The variation, as referred to above, between mean or averagesaturationconstants specific to particular groups of plants is of sufiicientmagnitude so that care and discretion must be exercised in the selectionof thegparticular group of plant types to be used as a basis for thedetermination of the percent quantity of any minor element utilized as acomponent of my fertilizer material.

Variations of this order, however, have not but in my experience I haverealized separations .fall without the so-called critical range of 3 022 9 cmF/gm.

if soil solution diffusion rate is considered, although it has beenfound necessary in this connection to utilize this entire critical rangeof specific surface depending upon the plant types which, are averagedas to their saturation constants for the kind of plants my newfertilizer is to be used upon.

In the preparation of specific surface specifications for the formswhich are to be utilized in my fertilizer I have frequently found itnecessary to take into consideration certain unusual soil types wherethe material was to be used and which would influence the carefullycalculated relative rates of solubility of such forms through the actionof base exchange, soil fixation and the emf/gm. to

excessor deficiency of either organic or colloidalmaterial in suchsoils, thus providing unexpected results. A low soil solution dispersionfactor due to unusual soil texture frequently is a dominant factor. Insome instances of this kind trial and lar to the method which has beenin vogue for the determination of quantity or percent applications ofthe major elements in the fertilizer industry since its inception, withthis difference, however, that the saturation constants specific to oneor more plants is used and then corrected for soil characteristics,rather than simply trial and error methods in the field'for all cropsand all soil types as is customary.

The preferred finished blended material containing the three or moredesired minor elements, and in a quantity considered most advantageousfor the use to which they are to be put, is in such a finely subdividedstate, all particles falling as they do within the critical range fromminus 200 mesh to one micron, that after'such blending-or admixing,segregation does not occur. This is important because thereafter nomatter how handled, equal distribution of the minor elements throughoutthe entire mixture is assured. This is not true in the range of particlesize above 74 microns;

No difficulties are encountered in a proper blending of the variousforms of the minor elebe influenced in such an environment unfavorably.r

If my new fertilizer is to be used for a specific crop which is grown inlarge quantities such as a field crop, i. e. cotton, corn or tobacco, itwould be best to use their saturation constants specific to the plantfor all elements used in compounding the particular fertilizer tobeutilized on each such individual crop. v

If my new fertilizer is to be used generally for certain types of truckcrops, it should be compounded by using the average saturation con--stants specific to a number of'such crops for all elements used incompounding the particular fertilizer to be utilized for each type, suchas the leafy crop group, the root crop group, pome crop group.

If my new fertilizer is to be used indiscriminately for all kinds andtypes of crops, a mean average saturation constant for all elements usedshould be utilized. Such saturation constants specific to the plant"should then be obtained from several types of field crops as well asseveral kinds of truck crops.

and fleshy ments when they have been comminuted so that they fall withinthe critical range since little or no aggregation is encountered withinthis range. important, likewise, because were this not true, an intimateadmixing of the various forms of the minor elements used could not beeffected, and therefore proper distribution not ensured.

My new fertilizer material should not be used except in combination withcomplete mixed fertilizer, if optimum results are to be obtained.

Such material is never ground to a fineness com parable to my newfertilizer material. The mixing of coarse and finely ground materialinvariably results in segregation so that unequal distribution wouldoccurinhandling and in the field, and to avoid this I find itadvantageous to granulate or pelletilize my finely comminuted fertilizermaterial, using any of the conventional Irrespective of which of theabove procedures is followed for arriving at a designated quantity inpercent weight to beused in my new fertilizer material, soilcharacteristics should be taken into consideration as previously setforth. Influencing factors considered as soil characteristics are todaywell known. Some of them would be soil fixation, base exchange, anexcess or lack of colloidal material which would influence the rate ofdiffusion of the soil solutions in the soil aggregate, 'etc., as well assoil pH.

The procedure outlined above for determining the designated quantity ofa minor element for either a specific crop, agroup of similar types ofcrops or miscellaneous crops of all kinds, giving due consideration tosoil characteristics is simimaterial.

methods, to a size which permits it being then mixed with regular mixedfertilizer and precludes segregation in this operation. There are twomethods which may be employed for this purpose. The first method whichmay be used is to granulate the finished product and such granulationmay be efiected by the introduction of a water-soluble salt which willact as a binder. I have found that as little as live percent by weightof certain water-soluble salts will effect a good granulation. The sizeof the granules may be controlled by slightly altering conditions in anyprocess used and larger amounts of binder may be employed if desired. Ihave found either urea or sodium nitrate quite satisfactory for thispurpose, although any salt which is sufficiently water-soluble may beutilized. The second method which may be employed for effectinggranulation is to incorporate designated quantities of .my newfertilizer material in any of the commercial fertilizer salts. This maybe done by either pelletilizing from the molten salts or by a process ofgranulation whereby occlusion of my new fertilizer material isaccomplished by aggregation. The first process when properly usedprovides a pellet and the second provides a granule, within which isoccluded the water-insoluble particles comprising my new fertilizer Thefirst method of granulation is more satisfactoryfor shipment to mixingplants where mixed fertilizer is prepared to specification. The secondmethod is more satisfactory for use by fertilizer manufacturers whogranulate their commercial product.

I claim: 1. A fertilizer. material comprising at least threesubstantially water-insoluble inorganic forms of the 64 reciprocallyassimilable minor elements, each form being a source of a designatedquantity of at least one of the minor elements,.and having a specificsurface within the range between 3 cm. /g'm. and gi each form beingpresent in the mixture in amount and having a specific surface effectiveto be gradually available to produce plant stimulation without causingobjectionable toxicity, the ratio of the specific surface of each saidform to that of any other form being substantially inverselyproportional to the ratio of their rates of solu-. bility.

2. A fertilizer material comprising at least three substantiallywater-insoluble inorganic forms of the 64 reciprocally assimilable minorelements, each form being a source of a designated quantity of at leastone of the minor elements, and each said form having auniformlydiminishing distribution of particle size by weight andhaving aspecific surface within the range between ments, such minor elementforms being occluded each form being present in the mixture in amountand having a specific surface effective to be gradually available toproduce plant stimulation with-- out causing objectionable toxicity, theratio of the specific surface of each said form to that of any otherform being substantially inversely proportional tothe ratio of theirrates of solubility.

3. A fertilizer material comprising at least -three substantiallywater-insoluble inorganic formsof the 64 reciprocally assimilable minorelements, each form being a source of a designated quantity of at leastone of the minor elements, and having a specific surface within therange between D8 D8 cmF/gm. each form being present in the mixture inamount and having a specific surface effective to be gradually availabletoproduce plant stimulation without causing objectionable toxicity, theratio of the emf/gm. and

specific surface of each said form to that of any other form beingsubstantially inversely proportional to the ratio of their rates ofsolubility, the mean particle size of each form being such as to givethe desired rate of solubility in the soil I upon which it is to beused.

4. A fertilizer, material comprising at least three substantiallywater-insoluble inorganiceach-form being present in the mixture inamount and having a specific surface effective to be grad- 20,000 2/ D8cm. gm.

cmF/gm. and

ually available to produc plant stimulation without causingobjectionable-toxicity, the ratio of the specific surface of each saidform to that of in at least one compound containing a major element, andhaving a specific surface within the,

range between each form being present in the mixture in amount andhaving a specific surface effective to be gradually available to produceplant stimulation without causing objectionable toxicity, the ratio ofthe specific surface of each said form to that of any other form beingsubstantially inversely proportional to the ratio of their rates ofsolubility. 6. A fertilizer material comprising at least threesubstantially water-insoluble inorganic forms of the 64 reciprocallyassimilable minor elements, each form being a source of a designatedquantity of at least one of the minor elements, and having a specificsurface within the range between cmP/gm. and cmF/gm.

cm'F/gm. and cmF/gm.

elements, each form being a source of a desig nated quantity of at leastone of the minor elements, and having a specific surface within therange between each form being present in the mixture in amount andhaving a specific surface effective to be gradually available to produceplant stimulation without causing objectionable toxicity, the ratio ofthe specific surface of each said form to that of any other formbeingsubstantially inversely proportional to th ratio of their rates ofsolubility, particles of the fertilizer material being bound in the formof: agglomerates by a water-soluble substance 'which includes at leastone major element.

8. A fertilizer material comprising at least three substantiallywater-insoluble inorganic forms of the 64 reciprocally assimilable minorelements, each form being a source of a designated quantity of at leastone of the minor ele- 14000 cmF/gm. and emf/gm.

forms of the 64 reciprocally assimilable minor elements, each form beinga source of a designated quantity of at least one of the minor elements,such minor element forms being occluded in at least on compoundcontaining a major element, and having a specific surface within therange between 1,000 20,000 D, D each form being present in the mixturein amount and having a specific surface effective to be graduallyavailable to produce plant stimulation withcmF/gm. and Cnl. /gll'l.

out causing objectionable toxicity, each said form having a uniformlydiminishing distribution of particle size by weight within said range,the mean particle size of each form being such as to give the desiredrate of solubility in a soil having a pH within the range of 4.5 to6.75.

10. A fertilizer material comprising at least three substantiallywater-insoluble inorganic forms of the 64 reciprocally assimilable minorelements, each form being a source of a designated quantity of at leaston of the minor elements, and having a specific surface within the rangebetween each form being present in the mixture in amount and having aspecific surface effective to be gradually available to produce plantstimulation without causing objectionable toxicity, each said formhaving a uniforml diminishing distribution of particle size by weightwithin said range, the mean particle size of each form being such as togive the desired rate of solubility in a soil having a pH within therange of 4.5 to 6.75, particles of the fertilizer material being boundin the form of agglomerates by a water-soluble substance.

11. A fertilizer material comprising at least three substantiallywater-insoluble inorganic forms of the 64 reciprocally assimilable minorelements, each form being a source of a designated quantity of at leastone of the minor elements, and having a specific surface within therange between emf/gm. and cmF/gm.

20,000 V cmP/gm. and D8 each form being present in the mixture in amountand having a specific surface effective to be gradually available toproduce plant stimulation without causing objectionable toxicity, eachsaid form having a uniformly diminishing distribution of particle sizeby weight within said range, the mean particle size of each form beingsuch as to give the desired rate of solubility in a soil having a pHwithin the range of 4.5 to 6.75, particles of the fertilizer materialbeing bound in the form of agglomerates by a water-soluble substancewhich includes at least one major element.

emf/gm.

source of a designated quantity of at least one of the minor elements,and having a specific surface within the range between 1,000 2 20,000 Tcm. /g1n. and T each form being present in the mixture in amount andhaving a specific surface effective to be gradually available to produceplant stimulation without causing objectionable toxicity, each said formhaving a uniformly diminishingdistribution of particle size by weightwithin said range, the mean particle size of each form being such as togive the desired rate of solubility in a soil having a pH within therange of 4.5 to 6.75, which comprises comminuting each form in a closedsystem wherein particles of proper size are removed together withsuperfines lying withcut the critical range, and particles requiringfurther comminution are returned to the system with material which hasnot been previously comminuted, and mixing the particles of desired sizeof each form.

13. A fertilizer material comprising at least three substantiallywater-insoluble inorganic cmF/gm.

forms of the 64 reciprocally assimilable minor elements, each form beinga source of a designated quantity of at least one of the minor elements,and having a specific surface within the range between cmHgm. and

cmF/gm.

three substantially water-insoluble inorganic forms of the 64reciprocally assimilable minor elements, each form being a source of adesignated quantity of at least one of the minor elements, and each saidform having a uniformly diminishing distribution of particle size byweight and having a specific surface within the range between at leastthree of the forms being present in the mixture in amounts and havingspecific surfaces effective to be gradually available to produce plantstimulation without causing objectionable toxicity, and the ratio of thespecific surface of at least one form to that of at least one other formbeing substantially inversely proportional to the ratio of their ratesof solubility, the availability of the minorelement ions afforded byeach other form being such that they are severally non-toxic.

emf/gm. and cm. /gm.

GRIFFITH H. RIDDLE.

CERTIFICATE OF GORREGTI'ON. 3 Patent Np. 2,280,151. April 21, 19LL2.

, GRIFFI'IIHZ H. RIbbm.

It is hreb; certifiedthat error appears in printed specificationof theabove numbered patent requiring correction as follows: Page 2,'f:L1-stcolumn, lines l9'and 20, for "differentiate" read "differentiatesline 21after "assimilation" insert a comma 11.11667, for "solid"' read -soil--;and second column, line 7, after ".suif icil.ency' strike out thecomma;' page 1 first column, line 66, for "nown'" read --k:nown--; andsecond column, line 5, for 'point" read --plant--; line 10, for "overapplication" read oven-application--; page 5, first column, 1111622, for"permiting" read --permittin g and that the said Letters Patent shouldbe read with this correction therein. that the same-may conform to therecord of the case in the Patent Office. Signs 1 an; sealed this 50thday of June, A. D. 19h2.

Henry Van Arsdale,

(Seal) Acting ConunissioneKofPatents.

